Sometimes ???remote.CONNECT_FAILURE???

Hello Zimbra Team,

sometimes i get the Error "???remote.CONNECT_FAILURE???".
After restarting Zimbra everything is fine .. on a random of time, the Error show's again.
What is ToDo ?
If there some WikiEntry to Debug this situation ?

Code:service.FAILURE
at com.zimbra.common.soap.Soap12Protocol.soapFault(So ap12Protocol.java:88)
at com.zimbra.common.soap.SoapTransport.extractBodyEl ement(SoapTransport.java:303)
at com.zimbra.common.soap.SoapTransport.parseSoapResp onse(SoapTransport.java:262)
at com.zimbra.common.soap.SoapHttpTransport.invoke(So apHttpTransport.java:253)
at com.zimbra.common.soap.SoapHttpTransport.invoke(So apHttpTransport.java:162)
at com.zimbra.common.soap.SoapTransport.invoke(SoapTr ansport.java:356)
at com.zimbra.common.soap.SoapTransport.invokeWithout Session(SoapTransport.java:342)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:660)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:622)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:617)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:610)
at com.zimbra.cs.mailbox.ZcsMailbox.sendRequest(ZcsMa ilbox.java:606)
at com.zimbra.cs.mailbox.OfflinePoller.waitsetRequest (OfflinePoller.java:120)
at com.zimbra.cs.mailbox.OfflinePoller.runPoll(Offlin ePoller.java:72)
at com.zimbra.cs.mailbox.OfflinePoller.run(OfflinePol ler.java:64)
at java.lang.Thread.run(Unknown Source)